Radiation attenuation corridor

ABSTRACT

A radiation attenuation corridor couples a radiation therapy room and a control room. The radiation attenuation corridor is made of a material that substantially absorbs ionizing radiation and substantially blocks the transmission of the ionizing radiation. Specific wall portions at the entrance of the corridor are covered with borated polyethylene (BPE). Specific wall portions diverge from an axis defined by the corridor by from about 10 degrees to about 45 degrees. The corridor thus leads out of the room and angles laterally across the wall of the therapy room, before angling again and opening to a safe room. The added angles in the radiation corridor increase the distance of radiation travel, and make the path more indirect, thereby increasing the contact of the radiation emissions with the radiation shielding and further attenuating the radiation.

TECHNICAL FIELD

The present invention relates generally to radiation shielding andparticularly to an improved radiation attenuation corridor for radiationtreatment facilities.

BACKGROUND

Radiation therapy utilizes several types of ionizing radiation, such asbeta-rays, gamma rays and x-rays, as well as high-energy protons andneutrons applied to malignant tissue to prevent and control the spreadof cancer. While ionizing radiation is capable of destroying canceroustissue, it is also capable of damaging healthy tissue inadvertentlyexposed thereto. Thus, a necessary precondition for treatment is thesafeguard of patients and personnel from accidental radiation exposure.

Various methods of shielding radiation in rooms and walls are known andin use in hospitals around the world. However, most of these methods areexpensive to manufacture and can be complicated to use. Many use complex“radiation mazes” composed of thick leaded walls with multiple 90-degreeturns, capped off with a heavy leaded door, often weighing thousands ofpounds. Typically, the many walls are composed of thick concrete orother materials known for their ability to absorb or block ionizingradiation. These methods have several drawbacks. The heavy doors requiremechanized assistance through automated motors and the like. This isboth time consuming and dangerous, as technicians and patients alike canget caught in the door if they are not careful. Furthermore, it is timeconsuming for a therapist whenever the patient requires adjustment orassistance. Moreover, the closing of a thick lead door has a negativepsychological impact on the patient who can feel entombed in the therapyroom. Additionally, such a room is expensive and the required footprintis very large, resulting in a lot of unusable space. Finally, it hasbeen known for these heavy doors to become stuck in the closed positiondue to motor or hinge failure. The patient is then alone in thetreatment room and must wait for the heavy door to be opened by someother means.

Some radiation therapy rooms have been created with a doorless entrysystem. See, Dawson et al., in “Doorless Entry System,” Medical Physics,vol. 25, No. 2 (February 1998), the entire disclosure and subject matterof which is hereby incorporated herein by reference. While such a systemmeets some of the above identified challenges, it is desired to increasethe radiation attenuation, by improving the system geometry.

SUMMARY

What is needed therefore is an improved radiation corridor thatsubstantially absorbs ionizing radiation and substantially blocks thetransmission of ionizing radiation from inside a room containing aradiation source, takes up as little room as possible, and iscost-efficient. Additionally, it is desirable to avoid the need for aheavy mechanized door.

The present disclosure comprises a radiation attenuation corridorcoupling a radiation therapy room and a safe area. The safe area isuseful as, for instance, a control room wherefrom a therapist canoperate radiation therapy controls to administer radiation to a patient,or other common area.

A preferred radiation corridor in accordance with the present disclosurebasically comprises a corridor which is open at one end to a radiationtherapy room and is open at another end to a control room or other site.The corridor comprises a first wall and a second wall, a floor and aceiling, all made of a material that substantially absorbs ionizingradiation and that substantially blocks the transmission of the ionizingradiation. The first wall and second wall portions are substantiallyparallel and diverge from an axis defined by the corridor by from about10 degrees to about 45 degrees. The corridor thus leads out of the roomand makes a 90 degree turn. The corridor then turns at an obtuse angleto traverse laterally across the wall of the therapy room, beforeturning at a second obtuse angle in the opposite direction of the first.Finally, the corridor makes another 90 degree turn before opening to asafe area.

In a preferred embodiment, selected portions of the walls of thecorridor are lined with radiation attenuation materials, including, butnot limited to, wood, plastics, polyethylene, graphite, wax, water orother suitable materials high in hydrogen concentration. In a furtherpreferred embodiment, the radiation attenuation material is boratedpolyethylene (BPE).

The placement of the angles in the radiation corridor increases thedistance radiation must travel, and makes the path more indirect. Thisincreases the contact of the radiation emissions with the radiationshielding. In other words, the ionizing radiation bounces between wallsections until it is absorbed before reaching the outer door openings.Coupling this novel geometry with the placement of BPE attenuates theradiation to a point where a door is not necessary for blockage ofradiation.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example, withreference to the accompanying drawings, in which:

FIG. 1 illustrates a schematic view of a radiation therapy areaincorporating a radiation attenuation corridor according to oneembodiment of the present disclosure.

FIG. 2 illustrates a schematic view of a radiation attenuation corridoraccording to another embodiment of the present disclosure.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring now to the drawings, preferred embodiments of the presentinvention are shown in detail. Although the drawings representembodiments of the present invention, the drawings are not necessarilyto scale and certain features may be exaggerated to better illustrateand explain the present invention. The embodiments set forth herein arenot intended to be exhaustive or to otherwise limit the invention to theprecise forms disclosed in the following detailed description.

Referring now to FIGS. 1 and 2, therapy room 10 includes a radiationsource 12, a first wall 14, a second wall 16 a third wall 18 and afourth wall 20. Fourth wall 20 includes an opening 22 leading to anaccess corridor 30, which extends along the first wall 14 away from thetherapy room 10.

Access corridor 30 comprises a therapy room access portion 32, anangular traverse portion 34, and a control room access portion 36, andis defined throughout by a first corridor wall 38 a-38 e, a secondcorridor wall 40 a-40 e, a floor and a ceiling. The first corridor wall38 a-38 e, second corridor wall 40 a-40 e, floor and ceiling are made ofmaterials that substantially absorb ionizing radiation and thatsubstantially block the transmission of the ionizing radiation. In apreferred embodiment, wall section 38 a has a length from about 5 ft. toabout 22 ft., wall section 38 b has a length from about 5 ft. to about20 ft., wall section 38 c has a length from about 3 ft. to about 15 ft.,wall section 38 d has a length from about 1 ft. to about 5 ft. and wallsection 38 e has a length from about 2 ft. to about 10 ft. Additionally,wall section 40 a has a length from about 2 ft. to about 10 ft., wallsection 40 b has a length from about 1 ft. to about 5 ft., wall section40 c has a length from about 3 ft. to about 12 ft., wall section 40 dhas a length from about 5 ft. to about 20 ft., and wall section 40 e hasa length from about 5 ft. to about 20 ft.

First corridor wall portions 38 a and 38 b meet at the junction of thetherapy room access portion 32 and the angular traverse portion 34.First corridor wall portions 38 a and 38 b are lined with BPE, much inthe manner that wall insulation is inserted between wall studs. Theyhave a preferred length from about 4 ft. to about 15 ft. In onepreferred embodiment, first corridor wall portions 38 a and 38 b arelined with BPE for a length of 8 feet in either direction from theirjunction point.

The therapy room access portion 32 opens at one end into the therapyroom 10 along the fourth wall 20, and extends outward from the therapyroom 10 a given distance. The therapy room access portion 32 is thencoupled with the angular traverse portion 34 of the access corridor 30at a corner. The angular traverse portion 34 traverses a portion of thefourth wall 20 while angling toward the interior of the therapy room 10.That is, the angular traverse portion 34 forms a first acute angle withthe therapy room access portion 32. The angle, α, between axis A andfirst corridor wall portion 38 c may be from 10 to 45 degrees.Similarly, the angle, β, between axis B and second corridor wall portion40 c may be from 10 to 45 degrees. Axis A and axis B are preferablysubstantially parallel, and relate generally to the axis defined by thecorridor. The first corridor wall portion 38 c and the second corridorwall portion 40 c of the angular traverse portion 34 can be parallel,such that angles α and β are identical, or they can converge, such thatangle α is greater than angle β. The angular traverse portion 34 is thencoupled with the control room access portion 36 at another corner, andthe control room access portion 36 leads further away from the center ofthe therapy room 10. The angular traverse portion 34 forms a secondacute angle with the control room access portion 36. In one preferredembodiment, the first acute angle and the second acute angle are suchthat the therapy room access portion 32 and the control room accessportion 36 are substantially parallel, though other embodiments arecontemplated depending on the specific application. In a most preferredembodiment, the distance between opposing walls is a minimum of sixfeet, to allow for the easy transfer of both patients and equipmentinto, and out of, the radiation therapy room.

In one preferred embodiment, an access door 50 is included at the end ofthe control room access portion 36 to prevent unauthorized orinadvertent access to the therapy room 10. In such an embodiment,sensors responsive to movement can be integrated with the door 50 toshut off the supply of radiation when someone enters the corridor 30.

In a further preferred embodiment, in which the door is absent, one ormore proximity sensors (not shown) are located at the junction of thecontrol room and the control room access portion 36 to detect entry intothe access corridor 30. Upon detection of entry into the access corridor30, the system could be set to shut down the radiation, to preventinjury to the entrant. Furthermore, one or more proximity sensors can beemployed near the junction of the control room and the control roomaccess portion, such that an audible or a visual warning can be givenwhen someone nears the control room access portion. This can preventinadvertent access to the control room access portion, therebypreventing the need to shut down the radiation, and save time for thetherapist and patient.

It is to be understood that the above description is intended to beillustrative and not limiting. Many embodiments will be apparent tothose of skill in the art upon reading the above description. Therefore,the scope of the invention should be determined, not with reference tothe above description, but instead with reference to the appendedclaims, along with the full scope of equivalents to which such claimsare entitled. The disclosures of all articles and references, includingpatent applications and publications cited herein are incorporatedherein by reference for all purposes.

Initial tests done on an embodiment of the doorless radiationattenuation corridor as described above have been performed, and theresults are listed in the table below. These results compare favorablywith currently mandated “acceptable” radiation levels, and demonstratethe viability of the disclosed system design. Rep Field Instant RateEnergy Size Photons Neutron Dose MU/min Gantry (MV) (cm) (μSv/hr)(μSv/hr) (μSv/hr) 500 0 15 0 2.30 7.00 9.30 500 0 15 10 2.40 7.00 9.40500 0 15 40 2.00 4.00 6.00 500 90 15 0 1.70 4.00 5.70 500 90 15 10 1.903.00 4.90 500 90 15 40 3.70 1.50 5.20 500 180 15 0 1.90 5.00 6.90 500180 15 10 2.20 5.00 7.20 500 180 15 40 1.80 2.80 4.60 500 270 15 0 2.809.90 12.70 500 270 15 10 2.70 6.00 8.70 500 270 15 40 2.20 5.60 7.80All readings are highest recorded of multiple measurements

1. A corridor which attenuates ionizing radiation, comprising: a firstwall having a length, a top portion and a bottom portion; a second wallhaving a length, a top portion and a bottom portion; a floorsubstantially co-extensive with said first and second walls andextending between said bottom portion of said first wall and said bottomportion of said second wall; a ceiling substantially co-extensive withsaid first and second walls and extending between said top portion ofsaid first wall and said top portion of said second wall; said firstwall, said second wall, said floor and said ceiling being formed of amaterial which substantially absorbs ionizing radiation and whichsubstantially blocks the transmission of said ionizing radiation frominside said corridor to outside said corridor; said first and secondwalls having portions which diverge from an axis defined by saidcorridor by from about 10 degrees to about 45 degrees.
 2. The corridorrecited in claim 1, wherein the material with which the first wall,second wall, floor and ceiling are covered is borated polyethylene 3.The corridor of claim 1, wherein at least a portion of the first wall iscovered with borated polyethylene.
 4. A corridor which attenuatesradiation, comprising: a first segment, a second segment and a thirdsegment; wherein the first segment is open to a room containing aradiation source; the second segment is coupled to said first segmentand extends at an acute angle therefrom, traversing a wall of the roomcontaining a radiation source; and the third segment is coupled to thesecond segment, and extends at an acute angle therefrom to open to asafe room.
 5. The corridor of claim 4 wherein a portion of the firstsegment has walls covered with boronated polyethylene.
 6. The corridorof claim 4 wherein the third segment includes a manual door openable tothe safe room.
 7. The corridor of claim 4 wherein the third segmentincludes a proximity sensor adaptable to stop the flow of radiation froma radiation source.
 8. The corridor of claim 7, further comprising asecond proximity sensor which when triggered warns that the first sensoris being approached.